1. Field of the Invention
This invention relates to butt joining methods. Such methods of this type, generally, allow fiber reinforced composite components to be butt joined in order to form a large integral structure.
2. Description of the Related Art
It is well known that the joining of metal matrix composite (MMC) components is difficult due to the interior ceramic reinforcements which may be particles, whiskers or fiber reinforcements. In the case of continuous internal fiber reinforcements, various methods of joining have been attempted. Fusion joining using tungsten inert gas, plasma arc and electron beam processes have been attempted without success. The chief problem with using these processes is that chemical and metallurgical reactions between the metal matrix and the ceramic reinforcement can occur which generate brittle butt welds.
In order to avoid the high temperature reactions, liquid phase interlayer bonding methods have been tried for this type of MMC with limited success. This joining technique which is essentially a brazing process would have limited high temperature applications since the interlayer has a lower melting temperature than the matrix. In addition, it was also found that the interlayer process was only applicable for simple lap joints, but was not well suited for butt joints. Most large structures used at elevated temperature cannot be composed of a series of lap joints and therefore, this type of joint would have limited application. Consequently, it would not be practical to use this type of joint for fiber reinforced MMC composites. Also, fabricating a butt joint with a layer of matrix material or interlayer between the components will not produce a suitable structure. The structure will easily fail in this local zone. Therefore, it is important to develop a joining process that can produce butt joints having a sufficient structural integrity for large structure applications.
It is apparent from the above that there exists a need in the art for a butt joining method which is capable of joining fiber reinforced composite components, and which at least equals the butt joining characteristics of known butt joining methods, but which at the same time can produce butt joints that have sufficient structural integrity for large structural applications. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.